1. Field of the Invention
Example embodiments relate to a display driver circuit, and more particularly, to a display driver circuit having separate grey-scale voltage generators according to red (R), green (G) and blue (B) colors.
2. Description of the Related Art
A thin film transistor (TFT) liquid crystal display (LCD) is widely used in notebook personal computers (PCs), monitors, etc., particularly as a color display.
A color LCD screen shows one color by combining colors passed through R, G and B color filters. A voltage applied to a source electrode of a TFT LCD in order to show each of R, G and B colors is referred to as a grey-scale voltage, which is output from a driver integrated circuit (IC) for driving a display. The brightness of a color varies according to the level of the grey-scale voltage.
According to the conventional art, the R, G and B grey-scale voltages are generated from one grey-scale voltage generator. In other words, a grey-scale voltage generator generates the same grey-scale voltages for R, G and B colors. This is based on the assumption that an electro-optic characteristic, that is, luminance is the same for R, G and B pixels. However, the luminances of R, G and B pixels are actually slightly different. In other words, the luminances of R, G and B pixels with respect to the same grey-scale voltage are not the same. For this reason, a G-white or R-black screen in which fine G or R color can be seen is output in a white or black screen.
To solve this problem, a display driver circuit has been provided with separate grey-scale voltage generators for respectively generating grey-scale voltages for R, G and B colors. However, the separate grey-scale voltage generators require a layout area three times as large as a conventional grey-scale voltage generator and also power consumption three times that of a conventional grey-scale voltage generator.
Furthermore, once a display driver circuit is implemented by separate grey-scale voltage generators, outputs of the separate grey-scale voltage generators are respectively applied to the R, G and B pixels even if the R, G and B pixels are driven by the same grey-scale voltage. Thus, all the separate grey-scale voltage generators must be driven, and power consumption is not reduced.